The depth of the water, therefore, has much to do with tidal irregularities. Out in the open ocean, where the tide is abyssmal—that is, about five thousand fathoms—the speed of the waves is amazing. Where the depth decreases to five fathoms the tide cannot travel more than fifteen miles an hour. In England, for example, which is surrounded by narrow land-broken seas, the result is that they get some of the most terrible and dangerous tidal races and currents to be found anywhere on the globe.
In the South Seas—particularly at Tahiti—the ebb and flow of the tide is perfectly adjusted. It is always full tide at noonday and at midnight, while at sunrise and sunset it is low water. The rise and fall seldom exceeds two feet; but once in six months a mighty sea comes rolling in and, sweeping over the corral reefs, nature’s breakwater, it bursts violently on the shore. Indeed, sometimes this tidal wave inundates entire islands.
In various parts of the world the tide creates various natural phenomena. There is the whirlpool between the islands of Jura and Scarba, on the west coast of Scotland, known as the “Cauldron of the Spotted Seas.” The Maelstrom upon the coast of Norway is another creation of the tide. The force of a heavy tidal current pushing up a wide-mouthed river, causes what is termed a “bore.” The most striking example of this tidal feature is seen at the mouth of the Amazon, where a moving wall of water, thirty feet high and from bank to bank, rushes inland from the ocean.
The waves raced by the Gullwing’s bulwarks with dizzy speed. We plowed on, gaining all we could in every reach, but noting likewise that the Seamew, when she was in sight, seemed to draw away from us. When we had beheld her in the mirage she must have been a long way behind.
I reckon Captain Bowditch prayed for foul weather. And he did not have to pray long in this latitude. We were in the district of the Boiling Seas. Fogs are frequent; gales sweep this section below the Horn almost continually—sometimes from one direction, sometimes from another. All the winds of heaven seem to meet here and gambol together.
“He’s runnin’ us into trouble, that’s what he ban doing,” croaked Stronson. “De old man, I mean. He iss not satisfied with the fair wedder; and who but a madt man vould crave for a gale down here under de Horn?”
But we younger fellows laughed at the old Swede. We were almost as much excited in the race between the two windjammers as were Captain Bowditch and Mr. Barney.
“Remember!” croaked Stronson. “The corpus lights wass not for nottings. Trouble iss coming.”
“But not necessarily trouble to the ship,” declared Tom Thornton. “Them St. Elmo’s fires foreruns death.”
“Dey ban mean bad luck, anyway,” growled Stronson.